After you select objects to print, the following dialog boxes are displayed:

• Send to 3D Print Service dialog box
• Create STL File dialog box
• The Autodesk 3D printing website, where you can select a print vendor

The following prompts are displayed.

Select solids or watertight meshes

Select the 3D solids or watertight meshes to be printed. A watertight mesh is a mesh
object with no gaps.As you select solids or watertight meshes, note the following:

• Blocks that contain solids or watertight meshes must be scaled uniformly.
• Only solids and watertight meshes within selected blocks and xrefs are included in
  the output (STL) file. All other geometry is discarded.
• Watertight meshes are converted to 3D solids based on the current value of the SMOOTHMESHCONVERT
  system variable. (Values of 0 and 1 create smoothed solids. Values of 2 and 3 create
  faceted solids.) 3DPRINT does not optimize, or merge, coplanar faces during this conversion.